An organic light emitting device (OLED) is a display device emitting light by use of an electroluminescent phosphor or an organic phosphor. The OLED drives a plurality of organic light emitting diodes to display an image, the organic light emitting diode includes an anode, an organic thin layer and a cathode. The organic thin layer usually has a multilayer structure including a light emitting layer (EML), an electron transport layer (ETL) and a hole transport layer (HTL), to improve the balance between electrons and holes, thereby improving luminescent efficiency. The multilayer structure may further include an electron injection layer (EIL) and a hole injection layer (HIL).
In an OLED, in order to display full-colors, red (R), green (G) and blue (B) light emitting layers may be patterned respectively. In order to pattern the light emitting layer, a shadow mask may be used in a case of a small-molecule OLED, and an inkjet printing method or a laser induced thermal imaging (LITI) method may be used in a case of a polymer OLED. By the LITI method, an organic layer may be finely patterned. The LITI method may be used for a large area, and an advantage of LITI method is a high resolution. A display with high pixels per inch (PPI) is a major trend of the current display device. In the existing OLED mass production technology, a fine metal mask (FMM) and a RGB side by side method is mainly used to achieve the full-color display of OLEDs. However, it is difficult to control the accuracy of FMM, so that it is difficult to achieve a high PPI OLED. In order to increase the density of pixels, in the related art there are mainly two solutions as follows.
1. As shown in FIG. 1, firstly, light emitting layers of sub-pixels of two colors, for example, R and G, are made simultaneously; then by using different optical thicknesses of the light emitting layers of the two sub-pixels, one of the colors, for example, R or G, is extracted by a micro-cavity effect; after that, when making a light emitting layer of a third color sub-pixel, the light emitting layer of the third color for example, B, may be formed in the entire pixel region. However, the OLED made in this manner, along with the perspective being changed, a color cast is very serious, and the luminescent efficiency of the light emitting layers of the two colors manufactured simultaneously may also be decreased.
2. As shown in FIG. 2, light emitting layers of same color sub-pixels in different pixels are deposited simultaneously by a FMM method with a larger opening. However, such manner may cause an arrangement sequence of sub-pixels inconsistent, resulting in jagged images in which lines are not continued when a screen is displayed.